Thread by @michaelmina_lab

IMPORTANT:

RAPID TESTS DO WORK WITH OMICRON

"But why are some people staying negative in the first days they have symptoms??"

This is expected. Symptoms don't = contagious virus
This is literally a reflection of the fact that vaccines are doing their job!

PLEASE READ

Rapid Tests work w Omicron

Omicron is mutated mostly in Spike
Rapid Tests don't detect Spike

They detect nucleocapsid (N)

Omicron has 4 mutations in N

2 were in alpha/delta and were fine

2 are in NTD - a non-immunogenic site - unlikely to impact rapid tests

2/

We can use this “new” relationship between symptom onset and infectiousness to our advantage!

It’s a feature, not a bug. Now that the world has pre-existing immunity, we have to adjust our thinking.

Newly Symptomatic and Ag neg?
Probably not infectious now… test again tmrw

3/

Pre Symptomatic contagion has been a very difficult aspect of this pandemic

It meant that to catch infectious ppl before they spread, you’d have to test frequently

But now we have immunity & it brings relationship closer to that of other resp virus-human interactions

4/

The reason other resp viruses often become symptomatic before contagiousness isn’t Bc they are different, it’s Bc we developed immunity to them when we were babies

But this virus emerged when most of us have been adults. So we’ve had to go through our baby stage as adults

5/

So now we are pushing things further in the right direction. We recognize the virus quickly after it lands in us, we develop symptoms, we kind of fight it off, then it often eventually wins, and grows fast AFTER immunity/symptoms started.

6/

Thus, if you are symptomatic and negative - although it means you’re prob not contagious at that moment, be very very cautious. Quarantine even if possible and test the next morning or that night. (Sometimes even longer)

7/

With Omicron, the virus is growing even faster than before so please DO take precautions if you have symptoms. Listen to your symptoms for a reasonable amount of time and retest even daily if possible.

8/

I want to comment on important items raised as a result of this thread.

1) I am primarily trying here to explain that it is expected for people to show symptoms earlier than before, as a result of vaccination and development of acquired immunity. This is the point of vaccines.

My point was that symptoms SHOULD be expected to arise early now that peoples immune systems don’t have to spend 5+ days realizing someone is infected with a new virus. Now our immunity kicks in fast and, with it, symptoms do too

2/

Additionally I should be more careful with my words. I am intending to state that the rapid tests are working just as well to detect Omicron virus as they were with Delta virus. For most part, they are not impacted by Omicron mutations in terms of detecting high virus load

3/

However,*IF* the whole dynamics of how Omicron is spreading has fundamentally changed compared to Delta then this is a different issue. If transmission is able to occur at low viral loads then this becomes a much more difficult virus to test for before transmission

4/

If Omicron is able to more efficiently replicate in bronchus (not measured in nasal swab), lyse & release from cells much more efficiently, then we may be in a situation where the amount of virus measured in the nose on any test may not correlate as well with exhaled virus.

5/

This doesn’t mean tests are not able to pick up Omicron but may mean the swab sampling for the virus may not be adequate to fully detect people as soon as they start transmitting.

We may need to think of an approach to collect breath and run on LFT…

6/

Nevertheless, all the data is in fact showing the rapid tests DO detect Omicron as well as they detected Delta.

Vaccines have changed the timing of symptoms wrt exposure and virus load, and if Delta is more effectively aerosolizing, that’s a different but major issue

7/

So Rapid tests are doing as well to detect Omicron as they did Delta - and the mutations would suggest this should be the case

But if whole dynamics of Omicron have changed in terms of ability to transmit, early quarantine w any symptoms should become common while testing

8/

Also - if looking at the graph - “exposed” should be shifted over to day 0. Sorry for that mistake.

I should add that we now have considerable data to back up the original hypothesis in this thread.

I detail it here, but in short it is that boosted people are esp prone to becoming symptomatic early - indicating early immune activation w existing immunity

https://twitter.com/michaelmina_lab/status/1488988413948829696